Postgres crosstab confusion - postgresql

Question

I'm trying to achieve the following from my data:
docid, yyyy, tiOne, tiTwo, tiThree, tiFour
d1 2011 txtA txtB txtC
d2 2012 txtD txtE txtF txtG
d3 2013 txtH txtI txtJ
d4 2013 txtK
This is how to recreate my data:
CREATE TEMP TABLE t (
docid text
, yyyy int
, timark text
, txtmark text
);
INSERT INTO t VALUES
('d1', 2011, 'tiOne', 'txtA'),
('d1', 2011, 'tiTwo', 'txtB'),
('d1', 2011, 'tiThree', 'txtC'),
('d2', 2012, 'tiOne', 'txtD'),
('d2', 2012, 'tiTwo', 'txtE'),
('d2', 2012, 'tiThree', 'txtF'),
('d2', 2012, 'tiFour', 'txtG'),
('d3', 2013, 'tiOne', 'txtH'),
('d3', 2013, 'tiTwo', 'txtI'),
('d3', 2013, 'tiThree', 'txtJ'),
('d4', 2013, 'tiOne', 'txtK')
;
This is my code
select *
FROM crosstab(
'SELECT docid, timark, txtmark
FROM t
ORDER BY 1,2') -- needs to be "ORDER BY 1,2" here
AS ct ("docid" text, "timark" text, "txtmark" text);
but I'm getting a completely confusing output as follows:
docid timark txtmark
d1 txtA txtC
d2 txtG txtD
d3 txtH txtJ
d4 txtK
The 'tiOne' data is not well structured, so it is hard to know precisely what is going to be in those columns, so it won't be easy to hard-code those values into the code

Answer 1

The crosstab query alias should contain the column names and types of the result set.
The result of the source query should be ordered by two columns: row identifier (docid) and category identifier (timark).
Unfortunately, the alphabetical order of the category names is not the expected one.
In this case use the form of crosstab function with two parameters.
The second parameter is a query that selects all categories in an expected order.
This form of crosstab allows also to have additional columns (yyyy) and properly shows incomplete data.
select *
FROM crosstab(
$$ SELECT docid, yyyy, timark, txtmark
FROM t
ORDER BY 1 $$,
$$ values ('tiOne'), ('tiTwo'), ('tiThree'), ('tiFour') $$)
AS ct ("docid" text, "yyyy" text, "tiOne" text, "tiTwo" text, "tiThree" text, "tiFour" text);
docid | yyyy | tiOne | tiTwo | tiThree | tiFour
-------+------+-------+-------+---------+--------
d1 | 2011 | txtA | txtB | txtC |
d2 | 2012 | txtD | txtE | txtF | txtG
d3 | 2013 | txtH | txtI | txtJ |
d4 | 2013 | txtK | | |
(4 rows)